Centrifugal compressor.



L. C. LGEWEN'STEIN.

vCENTBIFUGL COMPRESSOR. APPLICATION FILED IIINE so. me.

Patented Apr. 9, EEES.

2 SHEETS-SHEET l.

I Il...

Patented; p'. 9, M8.

2 SHEETS-SHEET 2.

. C. LOEWENSTEIN.

CENTRIFUGAL COMPRESSOR.

APPLICATION FILED JUNI: so. me.

iv'I,

l am? 'e nl f L lli-di senat-#str da@ -QUIS C. LGEW'EMETEN, F LYNN, MASSACHUSETTS, ASSIGNR T0 GENERAL ELECTREC COIMPNY, if AGRPORAIJION' DF NEVI YRK.

GENTRIFUGL CGMPRSSOR.

Specification of Letters Patent..

Patented Apr. 9, illll.

l Application filed J' une 30, 1916. Serial To. 10?.,923.

To all whom it may concern:

Be it .known that l, Leurs C. LOWEN- sinne, a citizen of the United States, residing at Lynn, in the county of Essex, State 5 of Massachusetts, have invented certain nevir A and useful improvements in Centrifugal Compressors, or which the following is a specication.

The present invention relates to centrifu gal compressors and to the governing mechanism therefor.

ln many instances it is necessary to vary y both the quantity and the pressure oi air' delivered by a compressor over Wide ranges especially in connection With converters use in the process of sinelting metals. For eX- lample, in one instance Withwwhioh l ,am familiar, the quantity of air required at the start is 2500 cubic feet of free air per minc nte, Which quantity is gradually vincreased in the course of substantially a two-hour run to 25,000 cubic feet of free air per minute, the pressure in the meanwhile also increasing./ y, The variation of quantity and pressure can readily be obtained when the compressor is driven by an elastic fluid turbine because.

the latter is capablev of being driven at widely varying speeds Without having its economy seriously impaired. v0n the other hand when the compressor is driven by an alternating current motorof the asynchronous type, for example, it is only possible to vary the speed over wide ranges at a great x5 sacriice in enomy of operation. Roughly,

it takes asdi motor at very low speeds as it does to opcrate it at ljull speed. This is due to the fact that current consuming or wasteful rev nice haette be included in the motor oir cui., and the lower the desired speed't-he greater will be the amount of resistance used. {vith its corresponding loss of energy. lt is nossible, however, to obtain some variations o. speed Without excessive losses duc to resistance, For example, a variation of speed from N00 lvl, to H00 R. l?. ll/l. is Withr`ood engine practice.

he obiect ci :ny invention is to so on gain construct the compressor, driving motor, and governing mechanism, that the output of vthe compressor can be UAA varied *from minimum to mann/num Without of energy. 55o o accomplish. this a multistage compressor speed variation.

-uch current to operate such a 'is' provided which has a number of outlet conduits opening into the supply main lea-ob lng to the point ot consumption instead of a single outlet conduit, as isthe common practice. ln each lconduisit is a valve for cut- 6o ting it into andl out of service, it being understood that only a single conduit. is in. service at a time. These valves may be op` erated by hand' or by motors' as desired. When motor operate'dpthey may be con- .65 trolled from a distance, for example, at thee: place Where the air is used instead of at the compressor, which is generally remote from the point of consumption.

lis before stated, an asynchronous alter- 70 nating current motor is capable of limited l, therefore, connect the first outlet conduit to the compressor at such a point that it Will deliver the desired quan-r tity of air'forfone portion of the cycle of 75 operation, While the speed of the motor is changing" from its minimum to its maximum.. A second outlet is connected to the come presser at such a point that it Will deliver with. the minimum speed of the motor sub- 8o stantially the same quantity and pressure of air as was previously delivered by the first outlet at maximum speed of the motor. A third outlet isor may be provided which, with. the minimum speed of the motor, de 85 livers substantially the same amount of air that the second did with maximum speed of the motor. j These conduits may be duplicated at Will. To state the matter in another Way, a step-by-step operation. is pro- 9u vided in which the motor operates at its predetermined minimum speedmat the start and is then increased 'to its predetermined maximum speed. A changeigthen made in the compressor outlet connections and the 95 cycle of -operation of the motor is repeated.

lrf each stage of the compressor is arranged to deliver air With substantially the same added increment or pressure, the outlet conduits Will-not be connected tothe sueces- 10o sive stages. For example, in an eight stage machine, the second, third, fifth, and eighth stages may be provided Withthese outlet conduits. 0n the other hand, if the impeller diameters enlarge from ithe inlet to 10o the final. stage in suoli manner that the added increment of pressure isy suiiioiently greater stage by stage, then each stage may be .provided With au outlet conduit.

The compressor is also provided. with a lio message 'ally decreasing the resistance in the motor circuit, and gradually increasiing,` the motor speed. When the speed has reached the maximum, say, 1400 it. P. the valve in outlet conduitv I is opened and that in 6 closed, At the time this change is made the i-heostat plates are quite close together and the speed of the compressor and its motor ai iubstantially at the maximum. This change of outlet will by reason o the increased quantity of air delivered cause the tioat i9 to assume a new and higher position, and cut resistance into the motor eircuit, thereby quickly decreasing its speed until the quantity of air and pressure delivered through outlet conduit 7 correspends at the reduced speed to substantially the same quantity and pressure of air which was formerly delivered by the outlet conduit 6 at maximum speedv of the motor. As the motor 26 continues to rotate the lead screw, the Weight 24 Will gradually increase the speed of the driving motor 30 to the maximum 'when outlet conduit 8 is Opened and conduit 7 closed, and the operation repeated as above described. From Fig. 2 will be seen in what portions of the complete cycle the different' discharge outlets are in service. From this figure it will also be seen that the quantity and pressure of the air delivered to the converter varies during the two and a half hour run from 2500 cubic feet of tree air per minute to 25,000 cubic feet of free air perininute. The pressure varies from about tivo lbs. per square inch to fteen. For any desired period of time after the last outlet conduit is opened the compressor operate at its full capacity, as indicated. These figures, itis to be under stood, are given as illustrations and not as limitations of my invention, since the cycle of operation can be modified to meet any de- \sired condition. if it be desired to change the rate of movement of the Weight 24 more or less resistance may be included in the circuit of the motor 26, as is usual in such. cases, and the motor can be temporarily stopped it' desired by opening the switch 3l. At the end of the cycle the Weight 24: can be disconnected from the lead screw and moved back by hand or in any other suitable manner.

As the compressor will generally be located in the power house and the valves 13 in thc converter house, a signal may be pro vided,l suoli as an incandescent lamp or bell 32 located in the converter house, to Warn the operator that the maximum speed of the drivingmotor for a given portion of the cycle has been reached, and that another discharge outlet should be opened. This may be (lone by having the Weight carryingl beam close the lamp or bell circuit by contacts 83 whenv it reach s its eXtreme position. The valves 13 may. however, be located in the power -house Which means a reduction in the amount of piping required.

In accordance with the provisions ot the patent statutes, I have described the principle of operation of my "invention, together with the apparatus which l now consider to represent the best embodiment thereof; but i desire to have it understoodthat the apparatus shown is only illustrative, and that the invention can be carried out by other means.-

1What l. claim as new and desire to secure by Letters Patent of the United States, is

The method of operating a multi-stage compressor which is driven by a motor having a limited range of economical speed, which consists in including a predetermined number of stages in service, increasing the speed of the motor from a predetermined low to a 'edctermined higher speed, cutting additional stages'into service and reducing the speed of the motor, and thereafter increasing the speed of the motor to said higher speed.w

2. ln combination, 'tumulti-stage centrifuga-l compressor arranged to operate from .no-load to full capacity, ,a driving motor therefor which has a limited range of operatingl speed, means for varying the number of stages of the compressor' in operation, and governing mechanism for varying the speed oit the' driving motor from a predetermined low to a predetermined higher speed for each setting of said means.

3. In combination, a multi-stage centrifugal compressor arranged to operate from 11o-load to full capacity, a driving motor therefor which has a limited range of `operating speed, valve controlled conduits lead ing from different stages of the compressor to the point oit' consumption, and governing mechanism responsiveto the flow of fluid through the compressor for increasing the speed of the driving motor from its pie determined minimum to its predetermined maximum each time one of said conduits is opened.

fi. ln combination, a multi-stage centrif ngal compressor having discharge outlets leading` from various determined stages 115 which are so arranged that each succeeding outlet after the first Will, at reduced speed of the drivingn motor, deliver substantially the same quantity and pressure of fluid asA was delivered by the preceding outlet With a greater speed of the driving motor, a driving motor `Whose speed may be varied be tiveen certain limits, and means for varying the speed of the motor.

5. in combination, a multi-stage centrit` ugal compressor having discharge outlets leading from various determined stages Which are so arrangedthat each succeeding outlet after the first vill, at the predetermined minimum speed of the driving motor, 130 

